RESUMO
BACKGROUND: The native potatoes (Solanum tuberosum subsp. tuberosum L.) grown in Chile (Chiloé) represent a new, unexplored source of endophytes to find potential biological control agents for the prevention of bacterial diseases, like blackleg and soft rot, in potato crops. RESULT: The objective of this study was the selection of endophytic actinobacteria from native potatoes for antagonistic activity against Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum, and their potential to suppress tissue maceration symptoms in potato tubers. This potential was determined through the quorum quenching activity using a Chromobacterium violaceaum ATCC 12472 Wild type (WT) bioassay and its colonization behavior of the potato plant root system (S. tuberosum) by means of the Double labeling of oligonucleotide probes for fluorescence in situ hybridization (DOPE-FISH) targeting technique. The results showed that although Streptomyces sp. TP199 and Streptomyces sp. A2R31 were able to inhibit the growth of the pathogens, only the Streptomyces sp. TP199 isolate inhibited Pectobacterium sp. growth and diminished tissue maceration in tubers (p ≤ 0.05). Streptomyces sp. TP199 had metal-dependent acyl homoserine lactones (AHL) quorum quenching activity in vitro and was able to colonize the root endosphere 10 days after inoculation. CONCLUSIONS: We concluded that native potatoes from southern Chile possess endophyte actinobacteria that are potential agents for the disease management of soft rot and blackleg.
Assuntos
Actinobacteria/fisiologia , Antibiose/fisiologia , Endófitos/fisiologia , Solanum tuberosum/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Chile , Endófitos/classificação , Endófitos/genética , Endófitos/isolamento & purificação , Pectobacterium/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Tubérculos/microbiologia , Percepção de Quorum , Streptomyces/classificação , Streptomyces/genética , Streptomyces/isolamento & purificação , Streptomyces/fisiologiaRESUMO
Se describió la capacidad de cinco cepas bacterianas para transformar un carbón de bajo rango (CBR), para ello se evaluaron cepas aisladas de microhábitats con presencia de partículas procedentes de los procesos de almacenamiento y lavado de carbón en la mina El Cerrejón (Colombia). Se realizaron ensayos de solubilización de CBR en medio de cultivo sólido y líquido, además de la decoloración de sustancias húmicas (SH) extraídas del CBR. Todas las bacterias evaluadas presentaron capacidad para biotransformar CBR en medio sólido, esta actividad es mayor cuando el CBR ha sido pretratado con ácido nítrico; en medio líquido se alcanzó una pérdida de peso de CBR hasta del 37% por acción de una cepa de Acinetobacter baumannii, acompañada de la aparición de hasta 8,06 mg/ml-1 de sustancias solubles con absorbancia a 465 nm; los cambios en el pH del medio sugieren que la actividad biotransformadora de CBR está asociada a la liberación de sustancias alcalinas; finalmente, se encontró evidencia para sugerir que las SH presentes en el CBR son transformadas por cometabolismo, posiblemente mediante reacciones de depolimerización, decoloración y repolimerización.
in this study were evaluated five bacterial strains isolated from microhabitats with high content of coal particles generated from storage and washing processes, in "The Cerrejón open coal mine (Colombia), their ability to biotransform a low rank coal (LRC) was described by testing solubilization on solid and liquid culture medium, as well as bleaching of humic substances (HS) extracted from LRC. All tested bacteria showed ability to biotransform LRC on solid medium, this activity is greater when the LRC has been pretreated with nitric acid; in liquid medium LRC reached 37% of weight loss by Acinetobacter baumannii strain, accompanied by the appearance of up to 6.8 mg/ml-1 of soluble substances with absorbance at 465 nm, changes in culture medium pH suggest that LRC biotransformations activity is associated with alkaline substances release, finally found evidence to suggest that HS contained within LRC are transformed by cometabolism, possibly by depolymerization reactions, bleaching and repolimerization.